narrated that Jaabir ibn ‘Abd-Allaah (may Allaah be pleased with him) said: On the day of Khaybar, the Prophet (peace and blessings of Allaah be upon him) forbade the meat of domesticated donkeys, but he granted us a concession allowing us to eat the meat of horses.

And there is another hadith where Rasullah said it is halal to eat wild donkey.

Now there are couple of questions that came into my mind :

What is the story behind prohibition at the day of khayber i mean what incident took place?